Dear group,

I'm using version 4.5.
When I'm using a CO2 concentration of 600 ppm  the grain yield (Grain Sorghum/Wheat),  I'm getting very high grain yields as compared to baseline.  I'm incorporating a onetime application of CO2 through environmental modification.  The values I'm getting are in the range (yield increase):
7-12%   (irrigated Grain Sorghum),  50-100% (rainfed Grain Sorghum)
23-35% (irrigated wheat), 50-100% (rainfed wheat)

Queries:
Why is the high yield? Is there other way to do it?
Do I have to change anything in the species file to get the correct responses for C3 (wheat) and C4 (sorghum) crops?
Please share if anyone has an experience similar problem and have any suggestions.


Thanks for time and help

George Paul
Kansas State University